1. Field of the Invention
The present invention relates to a method for forming an SBT (SrBi.sub.2 Ta.sub.2 O.sub.9) ferroelectric thin film. More particularly, the present invention relates to a novel method by which an SBT ferroelectric thin film superior in ferroelectric characteristics can be formed at such a low temperature as not to affect semiconductor device processes.
2. Description of the Prior Art
Usually, the formation of SBT thin films has been researched through various techniques, including sol-gel method, MOD method, laser ablation method, etc. Of them, the most popular is the MOCVD (Metalorganic Chemical Vapor Deposition) method. However, the current forming processes of SBT thin film in use, including MOCVD method, have a serious problem of being high in temperature. That is, a process temperature of about 750-800.degree. C. has been a significant obstacle in proceeding with conventional semiconductor device processes. To overcome this obstacle, much effort has been made. For instance, MOCVD-SBT thin films, which are currently evaluated to show optimal properties, are deposited at a temperature of 500-600.degree. C. but their ferroelectric characteristics are not expressed without carrying out a subsequent thermal treatment at a temperature of 750.degree. C. or higher (see, Li et al. Appl. Phys. Lett., 68(5), 616 (1996); Yang et al., Materials Letters, 30, 245-248 (1997)).